[neutralino]

I've never heard of the fourth dimension to be called "time and motion"; the fourth dimension in Einsteinian gravity is time. That is, it is the fourth dimension of a four dimensional spacetime manifold of which the remaining three dimensions are spatial dimensions. I don't understand your questioning of "what are dimensions." The number of dimensions of a space(time) are the number of degrees of freedom, or the number of coordinates that one needs to give to a point in order to determine its position uniquely. In four dimensional spacetime, this is 4; (t,x,y,z). Note that there is nothing to do with motion here; I can slice through the spacetime at a particular moment, and find the position of the particle, whether it is moving or not.